This invention is directed to a new and improved device for the detection of surface contamination due to radiation. In particular, the present invention relates to a new and improved device for detecting surface alpha contamination on various odd-shaped metal components.
Presently, there exists a requirement for the development of a detection device for measuring surface alpha contamination on odd-shaped metal components. This requirement arises because of the problem discovered in making a determination as to the disposition of metal working machinery that has been used in processing radioactive materials which emit alpha particles. It is the ultimate goal of the person involved in disposition of this machinery to decontaminate such machinery for (1) unrestricted reuse or (2) disposal as "clean" scrap. To accomplish these goals requires at least three process steps including (1) disassembly of the machinery, (2) decontamination of the disassembled components, and (3) testing to verify the adequacy of decontamination. The present invention is directed to a means of performing the verification procedure of step (3).
Upon disassembly of a piece of machinery one is left with a large number of differently (e.g. odd) shaped metal objects such as belts, brackets, gears, shafts, etc. The large reasonably flat surface articles are rather easily tested for surface alpha contamination with existing equiment. However, at present, there is no way to detect alpha contamination on the concave surface of most articles (e.g. teeth of bevel gears). This invention provides a means for detecting contamination on these types of articles.
The difficulty in detecting surface contamination on these types of articles originates from the fact that alpha particles (1) have a range in air which is quite short, and (2) can be stopped by almost anything as thick as a sheet of paper. Accordingly, to detect surface alpha contamination one must get the sensitive volume of the detector near enough to the surface being tested. Therefore, the choice of detectors appears to be limited to (1) one with a very thin, pliable, durable window which can wrap around and conform to an arbitrarily shaped article; (2) one or more custom built detectors for each object being tested, or (3) a very small detector which would fit into concave areas and could be used to scan the surface manually. The first choice appears to be impossible while the second and third options are clearly impractical considering the number and variety of the equipment involved. Accordingly, it is evident that the discovery of a practical means of detecting surface alpha contamination on odd-shaped metal components remains a problem.